Polyaniline is a well-known material of conductive polymers. In addition to the electric characteristics, polyaniline has advantages and characteristics of being synthesized by a comparatively simple process from an inexpensive raw material of aniline and possessing excellent stability in the air and the like, while exhibiting conductivity.
As a method for producing polyaniline, a method of polymerizing aniline or aniline derivatives by electrolytic oxidation or chemical oxidation has been known.
As the electrolytic-oxidation polymerization, methods of obtaining polyaniline on electrodes are described in JP-A-62-230825 and JP-A-62-149724. Although films with excellent electrical characteristics and the like can be obtained by electrolytic-oxidation polymerization, electrolytic-oxidation polymerization is generally more expensive than chemical-oxidation polymerization, is unsuitable for large-scale production, and involves difficulty in obtaining molded articles with a complicated shape.
On the other hand, in order to obtain a conductive polymer of aniline or aniline derivatives by chemical-oxidation polymerization, a step for protonating polyaniline, which is generally obtained in the state of a non-conductive base (so-called emeraldine base), by adding a dopant (doping agent) is necessary. However, since polyaniline in the state of a non-conductive base only scarcely dissolves in most organic solvents, the method is not suitable for industrial production. In addition, conductive polyaniline (in the state of a so-called emeraldine salt) produced after protonation is substantially infusible. It is difficult to manufacture a conductive composite material and its molded article in a simple manner from such a conductive polyaniline.
Several methods have been proposed for improving doping of polyaniline in the non-conductive base state and affinity of conductive polyaniline after doping with organic solvents.
Synthetic Metals, vol. 48, pp 91-97 (1992), for example, describes the use of proton acids having affinity with organic solvents such as dodecylbenzenesulfonic acid and camphorsulfonic acid (CSA) as dopants and their outstanding electrical characteristics.
JP-A-7-70312 discloses a method of doping polyaniline in a non-conductive base state using a damantane sulfonic acid dissolved in m-cresol as a dopant.
J. Phys.: Condens. Matter, vol. 10, pp 8293-8303 (1998) describes a method of doping polyaniline in a non-conductive base state using 2-acrylamide-2-methyl-propanesulfonic acid in a specific solvent (halogen-containing strong acid) such as 2,2-dichloroacetic acid, for example, as a dopant.
JP-A-2003-183389 describes, in the same manner as JP-A-62-149724, for example, a method of doping polyaniline in a non-conductive base state using 2,2-dichloroacetic acid as a solvent and di(2-ethylhexyl) sulfosuccinate as a dopant.
All of the methods described in the above-mentioned documents cannot be referred to as simple methods for producing conductive polyaniline because of inclusion of a step of doping polyaniline in the non-conductive base state. Moreover, molded articles made from these conductive polyanilines do not necessarily possess excellent electrical characteristics such as electric conductivity.
In view of the above situation, the invention has an object of providing a conductive polyaniline composition capable of producing a molded article possessing high conductivity, and a method for producing a conductive polyaniline complex and a composition comprising the same without producing polyaniline in a non-conductive base state.